1. Field
Aspects of the present disclosure relate to cathode active materials, cathodes including the same, and lithium batteries including the cathodes.
2. Description of the Related Art
As cathode active materials for a lithium battery, transition metal compounds such as LiNiO2, LiCoO2, LiMn2O4, LiFePO4, LiNixCo1-xO2, where 0≦x≦1, and LiNi1-x-yCoxMnyO2, where 0≦x≦0.5 and 0≦y≦0.5, and oxides of these transition metal compounds and lithium are used.
LiCoO2 is relatively expensive, and has a limited electric capacity, i.e., an electric capacity of about 140 mAh/g. In LiCoO2, when the charging voltage increases up to 4.2 V or greater, 50% or more of lithium is removed, and thus LiCoO2 exists in the form of Li1-xCoO2 where x>0.5. Oxides in the form of Li1-xCoO2, where x>0.5, are structurally unstable, and the electric capacity thereof is rapidly decreased during charging and discharging cycles.
A cathode active material such as LiNixCo1-xO2, where 0≦x≦1, or LiNi1-x-yCoxMnyO2, where 0≦x≦0.5 and 0≦y≦0.5, has poor swelling inhibition properties at high temperatures.
A lithium metal oxide in the form of Li[LixM′1-x]O2, where x>0 and M′ represents a plurality of transition metals, has an increased electric capacity, i.e., 250˜280 mAh/g. However, such a lithium metal oxide including an excessive amount of lithium has poor cycle properties and poor stability at high temperatures.